This invention relates to a biodegradable composition and a shaped article formed from the composition. The present invention is also directed to a method of producing a biodegradable material.
In view of the recent increasing problems of environmental pollution, the use of biodegradable plastics which are able to be decomposed by microorganisms when left in soil is being encouraged.
Japanese Published Unexamined Patent Application (Tokkyo Kokai) No. Hei-2-6689 discloses a biodegradable composite sheet composed of cellulose and chitosan. Though this composite sheet exhibits satisfactory biodegradability, it has been found that that the sheet involves a problem when used for industrial applications. Namely, this composite material is so stiff that utilization thereof is limited to specific applications. While it is possible to impart flexibility to such a composite sheet by incorporating a plasticizer, such as glycerin, sorbitol, ethylene glycol or polyethylene glycol, thereinto, the resulting sheet is found to gradually lose the flexibility when kept in contact with water and then dried because the plasticizer dissolves into the water with time.